Whitelist

A whitelist is a cybersecurity and access control mechanism that identifies a list of permitted entities or items. It specifies what is allowed to pass through a system or to be accessed, contrasting with a blacklist, which defines what is prohibited. Whitelists are often used to enhance security, filtering out unwanted or potentially malicious content, users, or applications. They function by granting access or permission only to those explicitly listed, assuming that everything else is inherently untrusted or restricted. This "trust-based" approach is widely implemented in email filtering, web security, software management, and user authentication.

Whitelist meaning with examples

• The email server uses a whitelist to ensure only trusted senders can bypass spam filters. Users were instructed to add the company's official domain to their whitelists, preventing important announcements from being marked as junk. This guarantees important communication reaches intended recipients. Conversely, any email not originating from the whitelist is treated with greater scrutiny.
• To access the company's secure network, users must first be on a whitelist, verified through employee verification processes and their device. This ensures only authorized employees can log in, preventing unauthorized access by outsiders. Each device is whitelisted by its unique identifier, and new devices require administrative approval. This promotes robust protection against cyber threats.
• The web application firewall employs a whitelist to allow connections from specific IP addresses, but block everything else. This practice limits the points of entry and helps safeguard against known vulnerabilities. New IP addresses must be explicitly added to the whitelist to grant access. Thus, a whitelist restricts network traffic to only trusted sources.
• For software installations, a whitelist is maintained that defines all approved applications allowed on employee computers. This restricts unapproved software, preventing potentially harmful downloads and unauthorized activities. Only software on the whitelist can be installed, minimizing risks. Any attempt to install software not on the whitelist will be blocked.